The present invention relates to an airbag system for a vehicle and, more particularly, to an airbag system for an automobile as a typical vehicle.
In recent years, automobiles as a typical vehicle have been increasingly popularly equipped both driver- and passenger-side airbag systems. Such airbag systems need properly deploy in car crashes, but must not needlessly deploy in absence of such emergencies in terms of labor and cost since exchange and adjustment are required once they have deployed. In the control of such airbag systems, it is important in, especially, the deployment control of the passenger-side airbag to check whether or not a passenger is sitting in the front passenger seat unlike the driver-side airbag, since often no passenger sits in the front passenger seat. In a vehicle equipped a passenger-side airbag, another problem is posed in its deployment control when a so-called child seat for an infant is attached to the front passenger seat. When a child seat is attached facing front to the front passenger seat, the passenger-side airbag must be permitted to deploy, but when a child seat is attached facing rear, the passenger-side airbag must be inhibited from deploying since shocks to the child seat and an infant who is sitting in that child seat upon deployment of the passenger-side airbag must be prevented.
As a method of solving such problem, for example, Japanese Laid-Open Patent No. 7-196006 discloses a technique for detecting the presence/absence of a child seat by arranging an optical distance sensor or the like in the vicinity of an airbag storage portion. On the other hand, Japanese Laid-Open Patent No. 8-58522 discloses a technique for controlling the necessity of deploying an airbag using both a distance sensor and a weight sensor equipped in a seat. Also, Japanese Laid-Open Patent Nos. 7-165011 and 7-267044 disclose a technique for detecting the presence/absence of a child seat via communications with the child seat using a transmission/reception mechanism arranged in a seat.
However, in these prior arts, when the distance sensor is used, determination precision has poor reliability. On the other hand, in the prior art that makes communications between the seat and child seat, no concrete disclosure is given as to control upon determining the necessity of deploying an airbag when the child seat is attached facing front or its position cannot be accurately determined.